/****************************************************************************
 *
 * Copyright 2023 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * arch/arm/src/armv7-a/arm_blocktask.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <stdbool.h>
#include <sched.h>
#include <assert.h>
#include <debug.h>

#include <tinyara/arch.h>
#include <tinyara/sched.h>

#include "sched/sched.h"
#include "group/group.h"
#include "up_internal.h"
#ifdef CONFIG_TASK_SCHED_HISTORY
#include <tinyara/debug/sysdbg.h>
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: up_block_task
 *
 * Description:
 *   The currently executing task at the head of the ready to run list must
 *   be stopped.  Save its context and move it to the inactive list
 *   specified by task_state.
 *
 * Input Parameters:
 *   tcb: Refers to a task in the ready-to-run list (normally the task at
 *     the head of the list).  It must be stopped, its context saved and
 *     moved into one of the waiting task lists.  If it was the task at the
 *     head of the ready-to-run list, then a context switch to the new
 *     ready to run task must be performed.
 *   task_state: Specifies which waiting task list should hold the blocked
 *     task TCB.
 *
 ****************************************************************************/

void up_block_task(struct tcb_s *tcb, tstate_t task_state)
{
	struct tcb_s *rtcb = this_task();
	bool switch_needed;

	/* Verify that the context switch can be performed */

	DEBUGASSERT((tcb->task_state >= FIRST_READY_TO_RUN_STATE) && (tcb->task_state <= LAST_READY_TO_RUN_STATE));

	/* Remove the tcb task from the ready-to-run list.  If we are blocking the
	 * task at the head of the task list (the most likely case), then a
	 * context switch to the next ready-to-run task is needed. In this case,
	 * it should also be true that rtcb == tcb.
	 */

	switch_needed = sched_removereadytorun(tcb);

	/* Add the task to the specified blocked task list */

	sched_addblocked(tcb, (tstate_t)task_state);

	/* If there are any pending tasks, then add them to the ready-to-run
	 * task list now
	 */

	if (g_pendingtasks.head) {
		switch_needed |= sched_mergepending();
	}

	/* Now, perform the context switch if one is needed */

	if (switch_needed) {
		/* Are we in an interrupt handler? */

		if (CURRENT_REGS) {
			/* Yes, then we have to do things differently.
			 * Just copy the CURRENT_REGS into the OLD rtcb.
			 */

			arm_savestate(rtcb->xcp.regs);

			/* Restore the exception context of the rtcb at the (new) head
			 * of the ready-to-run task list.
			 */

			rtcb = this_task();

			/* Restore rtcb data for context switching */

			up_restoretask(rtcb);

			/* Reset scheduler parameters */

			sched_resume_scheduler(rtcb);

			/* Then switch contexts.  Any necessary address environment
			 * changes will be made when the interrupt returns.
			 */

			arm_restorestate(rtcb->xcp.regs);
		}

		/* No, then we will need to perform the user context switch */

		else {
			struct tcb_s *nexttcb = this_task();
#ifdef CONFIG_TASK_SCHED_HISTORY
			/* Save the task name which will be scheduled */
			save_task_scheduling_status(nexttcb);
#endif

			/* Reset scheduler parameters */

			sched_resume_scheduler(nexttcb);

			/* Switch context to the context of the task at the head of the
			 * ready to run list.
			 */

			arm_switchcontext(&rtcb->xcp.regs, nexttcb->xcp.regs);

			/* arm_switchcontext forces a context switch to the task at the
			 * head of the ready-to-run list.  It does not 'return' in the
			 * normal sense.  When it does return, it is because the blocked
			 * task is again ready to run and has execution priority.
			 */
		}
	}
}
